This invention relates to the field of portable bag-shaft closing sewing machines and comprises an improved drive shaft and feed dog assembly oiling system.
Portable bag-closing sewing machines are used in packaging situations where the quantity of filled bags produced and requiring closure is not continuous and where heavy, stationary machines are not practical or available. Often the bags which require closure are filled with granular, fibrous or abrasive materials, and the portable machine is required to function efficiently over long periods under extremely dusty conditions and often abusive handling situations. In some applications, the portable machines see almost round-the-clock duty in assembly line or shipping dock environments, and it is virtually impossible to shelter all moving parts of the machine from the dusty, abrasive materials present in the working area. To insure continued, uninterrupted operation under these conditions, regular and complete lubrication of the machine is critical.
A self-oiling portable bag-closing sewing machine has been developed and is shown in U.S. Pat. No. 4,348,970, issued Sept. 14, 1982 and titled "Self-Oiling Portable Bag-Closing Sewing Machine". A further improvement of the oiling system of that patent is disclosed in U.S. Pat. No. 4,441,442, dated Apr. 10, 1984, and titled "Self-Oiling Portable Bag-Closing Sewing Machine With Pump".
As will be appreciated by those familiar with portable bag-closing sewing machines, the feed dog assembly, which cooperates with the needle to move fabric past the needle, is generally located at the lowermost portion of the sewing machine and is accordingly remote from the usual oil sources and difficult to lubricate. In the portable bag-closing lubrication devices and systems described in the above patent, the oil feservoir is located near the top of the machine, and while oil may be injected to one or more of the main drive shaft bearings, it otherwise originates at the upper portion of the machine and must work its way to the most distant reaches of the machine such as the feed dog assembly. Due to the need to keep the weight and size of the machine within workable limits for one hand operation, it is virtually impossible to carry large oil reservoirs or extensive internal oil supply conduits, extensive sumps, seals and the like with a portable machine.
While large, heavy, stationary pedestal-type bag closing machines of the type shown in U.S. Pat. No. No. 3,478,709 can carry such pumps, sump reservoirs and the elaborate internal and space consuming conduits, seals and the like, a commercially acceptable portable machine must remain compact, lightweight and easy to handle with a single hand for long periods of operation. Because of these weight and size limitations, oil delivery to the feed dog assembly of portable machines has been accomplished largely by gravity flow as the oil works its way downward from the upper regions of the machine. While some success has been achieved using the gravity flow delivery system, it has been found that much of the oil delivered to the machine is consumed or diverted before reaching the feed dog assembly. Accordingly, there remains a need to reliably, consistently deliver a greater quantity of oil to the remotely positioned feed dog assembly at the lower end of the machine, without requiring significant additional operator labor and without the introduction of additional space consuming components or extra weight. The present invention accomplishes these goals.